OLEDs have been developed for display applications due to their advantages like improved brightness, better power efficiency, faster response time, and coloring performance. However, the OLED devices are subject to diffusion of environmental moisture and oxygen, which may damage the organic materials and oxidize the conductive electrodes therein. This can lead to degraded performance and reduced lifetime of the OLED devices. Therefore, improved sealing processes are very important for their practical manufacturing, so as to protect the OLED devices from being penetrated by the environmental moisture and oxygen.
Recently, the frit sealing technique has been used to the OLED packaging, and it is proved to have effective prevention of moisture and oxygen. A display may include a cover plate or a base plate, which has a displaying region and a non-displaying region surrounding the displaying region. A frit can be dispensed on the non-displaying region and then baked in an oven at about 470, so that it can be glazed. The glazed frit is then emitted by a laser beam to be sintered, so that it can join the cover plate and the base plate tightly. The laser emission facilitates precise control of the frit curing. In the frit-sealing process, the frit glazing is performed before the frit sintering, so it can be recited as “pre-sintering”, also.
As described above, the high-temperature condition is used in the frit glazing, so it would be not applicable to flexible plastic substrates, such as a cover plate with a color filter in the white-light OLED device. Although the laser heating can also be used to replace the high-temperature baking in the pre-sintering process, a curve breach 10 is often formed at start or end locations of the laser emission, as shown in FIG. 1, leading to the failure in the subsequent laser sealing process of the device. Consequently, it is in need to develop a new frit pre-sintering method for the organic electronic or opto-electronic devices.